The present invention relates to polyolefin compositions which can be used to replace flexible polyvinylchloride (PVC or “vinyl”).
Flexible PVC compositions are the formulated polymer compositions used to create and manufacture a wide variety of intermediate applications including melt extruded single and multilayered cast, calendared, and blown film constructions, melt extrusion coated fabrics or other melt extrusion coated constructions, extruded profiles, extruded sheet and injection molded parts. These intermediate applications are then used to construct or manufacture end use products such as wall coverings, mattresses and bedding, seating, notebook and other book covers, packaging, many kinds of tubing, floor coverings, window treatments, labels and signage and many kinds of coated or laminated fabrics. Flexible PVC compositions are often composed of a plethora of other chemical additives that are critical to imparting the functional performance to the flexible PVC composition. The choice of such chemical additives used to modify the unmodified polyvinylchloride polymer to formulate the flexible PVC composition are chosen by one skilled in the art according to known properties that are imparted to the overall final composition. These chemical additives and the amounts used (the relative concentration based on the weight of the polyvinylchloride polymer) are chosen so that the final flexible PVC composition has the minimal and/or appropriate final properties required so that when the flexible PVC composition is melt extruded or formed into a final shape or part, the final end use application has the required, appropriate or minimal end use properties.
For example, U.S. Pat. No. 5,891,571 entitled Fire-Resistant PVC Formulation which issued on Apr. 6, 1999 to M. J. Herbert teaches the formulation of fire resistant flexible PVC compositions that have improved flame retardant properties. Herbert teaches that the use of relatively low levels of certain metallic stannates when used in combination with antimony trioxide and ammonium octamolybdate as flame retardant and smoke suppressant additives in flexible PVC compositions yields surprisingly low off gassing characterized by lower concentrations of smoke (lower smoke density results) and lower heat release rates when the flame retardant flexible PVC compositions are subjected to cone calorimeter tests per ASTM 1354. Obtaining lower smoke density and lower heat release rates is an important and desirable property especially as it applies to many of the end use applications in which an improved flame retardant flexible PVC composition could be used. If the composition taught by Herbert were used for wire and cable jacketing, for example, lower rates of smoke evolution and lower heat release rates from the partial combustion of the wire and cable jacketing present in the vicinity of the fire might allow a person escaping from a fire a longer time for egress. Therefore, one can see that Herbert teaches the use of certain combinations of additives that are to be used in the flexible PVC formulations that yield end use compositions that are suitable and even desirable for applications that might require the benefit of those unique additive modifications to the flexible PVC composition. Additionally, there are many other examples (See, for example, U.S. Pat. Nos. 3,941,908, 4,892,683, 5,013,782, 5,356,710, 6,114,425, 5,008,323) that demonstrate repeated attempts to improve flexible PVC compositions so that the functionality of the resultant flexible PVC compositions better satisfy and improve upon the end use properties and performance characteristics of the end use applications in which it is used. However, such improvements to flexible PVC compositions and the applications in which it is used do nothing to address the regulatory and commercial trend to completely eliminate the use of flexible PVC and/or many of its compositional additives used to formulate it for its various end uses.
Currently, there is a strong commercial trend for many manufacturers to move away from using flexible PVC to manufacture the products they produce. Recent new federal regulatory statutes, like the Consumer Product Safety Commission Improvement Act (CPSIA), provide good examples that reinforce the notion of a strong trend both domestically and globally of manufacturers choosing, or being forced, to use alternative polymeric materials as replacements for flexible PVC to create the end use products they produce. For example, there are a great number of child care products that have required the use of a flexible PVC laminated films and coatings in order to provide quick clean up features to juvenile care products like bedding, cribs, blankets, clothing, play pins, etc. Often these child care products are constructed in such a way that the flexible PVC film is laminated onto a substrate and decoratively printed. The end use “film coated fabric” or “laminated fabric” is ideal for use in the aforementioned juvenile care products, in the bedding ticking for example, and as a further functional requirement needs to remain soft and pliable to the touch and handling. In the case of juvenile bedding, federal law (CPSIA, above) now prohibits the soft, pliable, durable, highly decorative and economical juvenile bedding ticking from containing certain phthalate plasticizers which typically are an important, if not critical, flexible PVC additive that imparts various important flexible and other mechanical properties to the flexible PVC film composition. Additionally, the same flexible PVC laminated fabric needs to allow the mattress it is used to construct to comply with another recent federal statute governed by compliance with the Standard for the Flammability (Open Flame) for Mattress Sets, 16 CFR Part 1633. Thus, it appears that in the case of juvenile care products that have historically been manufactured using flexible PVC laminated fabrics, and especially juvenile care products made with flexible PVC laminated fabrics that require flame retardancy, manufacturers of such juvenile care products are being forced to identify and use alternative polymeric compositions that have similar or acceptable functionality and economics of flexible PVC to manufacture their products in order to comply with federal safety statutes.
In addition to statutory reasons for the commercial trend towards using alternative, but functionally equivalent, replacement polymers for flexible PVC, there is increasing pressure to do so being imposed upon various large companies, including leading retailers and technology leaders, which have been making public marketing announcements that they will voluntarily eliminate or reduce their use of flexible PVC to manufacture or package their products. For example, Microsoft announced that by the end of 2005 it will have completed its PVC packaging phase out, which has already resulted in the elimination of 361,000 pounds of PVC since July, 2005. Crabtree & Evelyn, an international manufacturer and retailer of personal care products, toiletries, home fragrance products and fine foods, announced it will phase out PVC in its packaging. Crabtree & Evelyn has already begun to phase out PVC in existing and all new product lines, and is developing a complete PVC phase out timeline. Kaiser Permanente, the largest non-profit health care system in the U.S. announced that it was phasing out PVC wherever possible in millions of square feet of new construction to be built over the next decade. Kaiser vendors have developed PVC-free wall protection products and PVC-free carpeting. Other recent PVC phase-out announcements include the following:                Catholic Healthcare West, a healthcare system with 40 hospitals, announced on Nov. 21, 2005 that it awarded a five year, $70 million contract to B. Braun to supply CHW with PVC-free and DEHP-free (a common phthalate plasticizer) IV systems.        Hewlett Packard (HP) announced on Nov. 1, 2005 that it plans to eliminate its remaining uses of PVC as safer alternatives become available. The company has removed PVC from all external case parts. In correspondence with HP, they noted that they were eliminating all PVC packaging. The Computer Take Back Campaign has worked with HP and other electronic companies to replace PVC and other harmful materials of concern with safer alternatives.        Wal-Mart announced on Oct. 24, 2005 that it will phase out PVC in its private label packaging over the next two years.        Firestone Building Products Company, the world's largest manufacturer of commercial roofing, closed down its PVC line in late 2005 in favor of safer materials. This represents some six thousand tons of PVC production annually.        Shaw Industries Inc. ran its last production of PVC carpet backing at the beginning of 2005, replacing it with EcoWorx, a cradle-to-cradle product that can be sustainably recycled, has less embodied energy than PVC carpet tiles, and maintains equal or greater performance.        Johnson and Johnson announced it has set a goal to eliminate PVC in its primary packaging, and it is actively engaged with suppliers to identify alternatives to replace existing PVC packaging and avoid PVC use in future products.        
All of the foregoing examples of major manufacturers and retailers are part of a broader economic trend in which US businesses are increasingly eliminating the use of flexible PVC compositions from the manufacture of their products and packaging of the products and instead announcing the use of what is perceived as safer and more environmentally sustainable alternatives.
Other major companies seriously affected by the current global economic recession, which are trying to recoup lost revenues are faced with following the larger companies' environmental marketing lead, and they are trying to either differentiate their products as more environmentally sustainable or comply with the aforementioned regulatory statutes as well.
At the forefront of negative marketing that is common is the fact that flexible PVC has been found to release dioxins when burned or overheated during extrusion processing of flexible PVC polymeric compositions. Dioxins are considered extremely toxic and have been found in some studies to cause cancer and harm the immune and reproductive systems. Studies have shown plasticizers such as phthalates have migrated out of PVC consumer products, exposing people to toxic additives linked to reproductive defects and other health problems.
Further, PVC cannot be effectively recycled due to the many incompatible additives used to soften or stabilize PVC, which can catastrophically contaminate a recycle stream when other polymeric thermoplastics are present in the recycle batch. Therefore, flexible PVC is increasingly being eliminated as an option when developing polymeric compositions for end use applications. More importantly, and of particular relevance to the present invention, is the need to replace the use of flexible PVC compositions in existing applications or where flexible PVC would have been the polymer composition of choice if it were perceived to be an environmentally sustainable option in new applications. More particularly, the choice of polymeric compositions that can economically be used to replace flexible PVC use in the manufacture of films, films laminated onto substrates, films directly extruded onto fabrics, yarns and other substrates that meet or exceed the regulatory, safety, flame retardant, mechanical performance, flexibility, and ease of processing that is either now required or well established from historical use of flexible PVC in existing end use applications. These end use applications include, but are not limited to, automotive interiors, wall coverings, upholstery, advertising banners and films, tenting, coated yarns and coated yarn fabrics, window treatment fabrics, and floor covering applications.
Polyolefins comprise the largest volume of thermoplastics consumed globally. It is well known in the art that polyolefins have many uses and can be combined with a plethora of additives and colorants to yield wide variety of useful end use properties for numerous end use applications. Of particular interest is the ease of processing, competitive economics, ease of chemical and down stream modification, excellent availability, ease of recycling, and an increasingly more chemically efficient methods of imparting flame retardant properties. For example, in U.S. Pat. Nos. 6,384,123 and 6,437,035, Young teaches the use of polyolefinic elastomeric compositions with improved mechanical, melt processing, and flame retardant properties for use in various film applications. In particular, Young teaches, in U.S. Pat. No. 6,384,123 that his polyolefin elastomeric film's composition contains, among other additives, a filler, aluminum trihydrate, that yields a composition with a limited oxygen index of 22. An oxygen index of 22 is considered to be “barely flame retardant” as ambient air at sea level contains about 21% oxygen. Therefore, Young improves on his invention further when he teaches in U.S. Pat. No. 6,437,035 a similar, yet improved polymeric composition used for similar applications where he has employed the use of halogenated flame retardants with the use of flame retardant synergists and smoke suppressants and/or hydrated mineral fillers like aluminum trihydrate and magnesium hydroxide to obtain much better flame retardant performance yielding limited oxygen indices of 26 to 31. While Young teaches this compositional use in films of 20 mils or less, Young does not teach that his polymeric compositions impart flame retardant characteristics to the substrates to which they are adhered, only that they are capable of being handled so that they may be laminated onto supporting scrims and the like. Also, the use of halogenated flame retardants in elastomeric polyolefin compositions to achieve higher oxygen index numbers and improved flame retardant properties while achieving an amorphous composition with a wide enough processing window so that the composition can be processed by a calendar to obtain films of 0.010 inch (10 mils) thickness as taught by Young is at the expense of using high levels of described halogenated flame retardants and antimony synergists resulting in higher raw material costs, higher processing costs, toxic off gassing during combustion and little to no chance of being able to extrude his compositions using standard polyolefin extrusion techniques, which is by single or twin screw extrusion methods, not calendaring. As he indicates in the detailed description of his invention, calendaring a polymer is usually reserved for completely amorphous polymeric compositions such as flexible PVC.
Further improvements to flame retardant polyolefinic compositions are taught by Costanzi in United States Patent Publication No. US2008/0214715 which teaches the use of certain synergistic mixtures of hypophosphorous acid metal salts and halogenated organic compounds. Of particular interest is his choice of their use in “moulding” compositions to achieve high levels of flame retardancy, particularly Underwriters Laboratories UL-94 specification. Unfortunately, Costanzi never teaches the use of his novel flame retardant technology for use in other applications, such as polyolefin elastomeric extruded films, blown films, cast extrusion coated films onto substrates like fabrics and scrims, calendered films, coated yarns and as an additive for fiber and yarn applications.
There are many end use applications such as automotive interiors, wall coverings, upholstery, advertising banners and films, tenting, coated yarns and coated yarn fabrics, window treatment fabrics, and floor coverings where elastomeric polyolefin polymer compositions could be used if only one could achieve high levels of flame retardancy, ease of processing, lower extrusion and down stream conversion costs, little to no toxic off-gassing, low smoke density during combustion, excellent mechanical properties, desirable hand characteristics and flexibility, ease of printing, excellent adhesion to a variety of substrates, low specific gravity and overall low raw material costs.